Hydraulic system for platen press



June 29 1965 s. LUDWlG 3,191,524

HYDRAULIC SYSTEM FOR PLATEN PRESS Filed Sept. 4, 1963 2 Sheets-Sheet l ,\\T" r I H I S I Y II; I 2 M1 6" A GIG/Q6 LUDk/IG INVENTOR.

United States Patent 3,191,524 HYDRAULIC SYSTEM FOR PLATEN PRESS Georg Ludwig, Schwelm, Germany, assignor to Wagener & Co. Maschinenfabrik, Schwelm, Germany Filed Sept. 4, 1963, Ser. No. 306,662 Claims priority, application Germany, Sept. 4, 1962, W 32,896 9 Claims. (Cl. 100269) My present invention relates to hydraulic presses of the type having a movable platen, usually of rectangular shape, which is forced against a stationary bed plate by a series of hydraulically actuated pistons.

In such presses it is usually impractical to provide each piston cylinder with an individual fluid-supply line having its own manometer and shut-01f valve, as would be desirable for the purpose of enabling deactivation of any defective cylinder Without interfering with the operation of the rest of the hydraulic system. It has therefore been the practice to group the cylinders in a plurality of rows and to assign to each row an individual branch conduit having a gate valve for effectively disconnecting it from a common main conduit and, therefore, from the source of hydraulic fluid (i.e. a high-pressure pump) working into the latter. If, now, the pump pressure cannot be maintained because of a leaking cylinder in one of the rows, the location of the leak is ascertained by a quick stopping of the pump whereupon the fluid pressure in the branch serving the affected row, elg. as determined by a manometer preceded by a check valve in that branch, drops off more rapidly than in the other branches, thus permitting the trouble to be isolated. Another possibility is to cut off one branch after the other and to determine the condition under which the pump pressure returns to normal. In each case it will be necessary to inactivate the. cylinders of an entire row until the leak can be repairedf With many types of presses, e.g. those used to fashion linkages inmaking or repairing endless conveyor belts for mining installations and the like, it is important to maintain a reasonably uniform contact pressure over the entire press platen so that the loss of a whole row of piston cylinders may be detrimental, particularly if the alfected row extends along one of the edges of the array. It is, therefore, the object of my invention to provide means for maintaining at least a partial pressure in a row of cylinders including a leaky or otherwise defective unit so that operations can be continued until at least the highpriority work has been completed.

In accordance with my invention I assign two or more branch circuits to each row of piston cylinders, the cylinders of the row being divided into subgroups of n cylinders each where his the number (cg. two) of branches assigned; each cylinder of a subgroup is then connected to a respective branch so that, if it should become defective, its companion cylinder would continue to operate and only the cylinders sharing a common branch line with the defective element would have to be deactivated. More specifically, the invention provides for juxtaposing the cylinders of each subgroup more closely than the subgroups themselves, even to the extent of letting the several cylinders of a subgroup actuate a common piston.

The invention will be described in greater detail with reference to the accompanying drawing in which:

FIG. 1 is a perspective view of a hydraulic system and associated parts of a platen press embodying the invention;

FIG. 2 is a diagram of the hydraulic circuits forming part of the system;

FIG. 3 illustrates a modification of the circuits of FIG. 2; and

3,191,524 Patented June 29, 1965 ICC FIG. 4 shows, in axial section, a dual piston cylinder adapted to be used in the system of FIG. 2 or 3.

FIG. 1 shows a part of a hydraulic press comprising a bed 1, a stationary plate 2 supported thereon and a movable platen 3 vertically displaceable with reference thereto, a load 10 being disposed between the two press members 2 and 3. Several yokes 4 rise from the bed 1 and serve as supports for a series of hydraulic cylinders 6 provided with pistons 6'. The cylinders 6 and their pistons 6' are arrayed in three parallel rows extending in the direction of the majoredges of the rectangular press members 2, 3. Hydraulic fluid is supplied to these cylinders via a number of conduits which have been generally designated 7 in FIG. 1 and will be seen in FIG. 2 to comprise three pairs of parallel lines 7a, 7b, each pair being assigned ,to a respective row of cylinders. The diagram of FIG. 2 also shows the cylinders of each row divided into subgroups of two cylinders each, i.e. a left-hand cylinder 6a and a right-hand cylinder 6b. The two pistons respectively actuated by a pair of closely juxtaposed cylinders 6a, 6b, are interconnected by a common foot plate 6" (see also FIG. 1) which bears upon the platen 3. The foot plates may merely bear upon the platen 3, which is downwardly (vertically) urged by the cylinders, or may be connected to the platen for upward entrainment by the pistons as they. rise.

A source of high-pressure hydraulic fluid, shown as a pump 11, works into a main conduit 12 to which each pair of branch conduits 7a, 7b are connected by way of a short line section 13. The cylinders 6a of a row are all connected in parallel to the associated branch 7a whereas cylinders 6b are connected in like manner to the companion branch 7b. Each branch 7a, 7b of each pair includes, at the end joined to its feeder line 13, a check valve Sand agate valve 9 in series therewith; a manometer 14 is inserted in the conduit just beyond the check valve to facilitate ascertainment of a leakage in a cylinder served bythe respective line. A further manometer 15 in the mainline 12 measures the delivery pressure of pump 11.

If the manometer 15 registers an unusual drop in pressure, the pump 11 is quickly arrested so that an inspection of the manometer 14 will reveal the branch with which the defective cylinder is associated. If this happens to be one of cylinders 6a, the valve 9 in the cones ponding branch 7a is closed so that all the remaining cylinders 6a are inactivated whereas the cylinders 6b keep operating as before. Each foot plate 6 thus continues to bear, albeit with reduced force, upon the platen 3 so that the press remains in satisfactory working condition.

FIG. 3 shows a set of four branch conduits 7a, 7b, 7c, 7d connected in parallel to a common supply line 13 to feed subgroups of four cylinders 6a, 6b, 6c, 6d in a row of piston cylinders forming part of an array generally similar to that of FIG. 2. In this case each subgroup of cylinders consists of two cylinder pairs 6a, 6b and 6c, 6d, the pistons of each cylinder pair again acting upon a common foot plate 6". Although all the pairs 6a, 6b and 6c, 6d are shown similarly spaced from one another, it will be understood that, if desired, all the cylinders 6a-6d of a subgroup could be closely juxtaposed and provided with a single foot plate instead.

FIG. 3 also illustrates the possibility of using but a single check valve 8 for each set of branch conduits associated with a single row of cylinders. Check valve 8 is inserted for this purpose in the common supply connection 13, in cascade with a manometer 14; individual gate valves 9 are provided in each branch 7a-7d. If a cylinder fails, pump 11 is arrested as before and the valves 9 of the defective row, identified by a low reading of its manometer 14, are successively closed and re-opened (with intervening restarting and stopping of pump 11) until the branch leading to the leaking cylinder has been located. This branch is then maintained disconnected frorn'supply line 13 until the defect has been cured.

In FIG. 4 I have shown a dual cylinder 16 divided into a pair of chambers 16a, 1612, each chamber enclosing a head 16a, 16b of a common piston 16'. Extensions 17a, 17b of respective branch lines 7a, 71) (FIG. 2) terminate at the chambers 16a, 16b. Piston 16' carries an individual foot plate 16" if used in an array of the type shown in FIG. 2; if incorporated in a system as illustrated in FIG. 3, it may be juxtaposed with a second dual cylinder and share a common foot plate therewith.

It will be apparent that each of the pairs of branch lines 7a, 7b in FIG. 2 may be provided with a single check valve 8 and manometer 14, instead of individual manometers and check valves, as illustrated in FIG. 3 and that further modifications of the system herein disclosed are possible without departing from the spirit and scope of my invention as defined in the appended claims.

I claim:

1. A hydraulic system for actuating a movable press platen, comprising a plurality of piston cylinders grouped in several rows, said cylinders being provided with piston means bearing upon said press platen; a main conduit leading to a source of fluid under pressure; a plurality of branch conduits connecting said main conduit with said cylinders, the number of said branch conduits being at least twice the number of said rows, each of said rows having a plurality of branch conduits assigned to it and having its cylinders dividedinto subgroups of at least two cylinders each, the cylinders of each subgroup being individually connected to respective branch conduits assigned thereto; check-valve means in the fluid-supply path of all the cylinders of a row between the cylinders and said main conduit; and individual shut-oflf means for said fluid in each branch conduit between said main conduit and the cylinders connected thereto. a

2. A system as defined in claim 1 wherein said checkvalve means comprises an individual check valve in each branch conduit adjacent said shut-off means.

3. A system as defined in claim 1 wherein said checkvalve means comprises a single check valve in a common supply line for all the branch conduits assigned to a row.

4. A hydraulic system for actuating a movable press platen, comprising a plurality of piston cylinders grouped in several rows, said cylinders being provided with piston means bearing upon said press platen; a main conduit leading to a source of fluid under pressure; a plurality of branch conduits connecting said main conduit with said cylinders, the number of said branch conduits being at least twice the number of said rows, each of said rows having a plurality of branch conduits assigned to it and having its cylinders divided into subgroups of at least two cylinders each, the cylinders of each subgroup being juxtaposed more closely than the subgroups of each row, the cylinders of each subgroup being individually connected to respective branch conduits assigned thereto; check-valve means in the fluid-supply path of all the cylinders of a row between the cylinders and said main conduit; and individual shut-off means for said fluid in each branch conduit between said main conduit and the cylinders connected thereto.

5. A hydraulic system for actuating a movable press platen, comprising a plurality of piston cylinders grouped in several rows, said cylinders being provided with piston means bearing upon said press platen; a main conduit leading to a source of fluid under pressure; a plurality of branch conduits connecting said main conduit with said cylinders, the number of said branch conduits being twice the number of said rows, each of said rows having a pair of branch conduits assigned to it and having its cylinders divided into subgroups of two cylinders each, the cylinders of each subgroup being juxtaposed more closely than the subgroups of each row, the cylinders of each subgroup being individually connected to respective branch conduits assigned thereto: check-valve means in the fluid-supply path of all the cylinders of a row between the cylinders and said main conduit; and individual shutoff means for said fluid in each branch conduit between said main conduit and the cylinders connected thereto.

6. A system as defined in claim 5 wherein the two cylinders of each subgroup are combined into a dual cylinder with common piston means.

7. A hydraulic system for actuating a movable press platen of generally rectangular shape, comprising a plurality of piston cylinders grouped in several rows parallel to two sides of the press platen, said cylinders being provided with piston means bearing upon said press platen; a main conduit leading to a source of fluid under pressure; a plurality of branch conduits connecting said main conduit with said cylinders, the number of said branch conduits being at least twice the number of said rows, each of said rows having a plurality of branch conduits assigned to it and having its cylinders divided into subgroups'of at least two cylinders each, the cylinders of each subgroup being individually connected to respective branch conduits assigned thereto; check-valve means in the fluid-supply path of all the cylinders of a row between the cylinders and said main conduit; and individual shut-off means for said fluid in each branch conduit between said main conduit and the cylinders connected thereto.

8. A hydraulic system for actuating a movable press platen of generally rectangular shape, comprising a plurality of piston cylinders grouped in several rows parallel to two sides of the press platen, said cylinders being provided with piston means bearing upon said press platen; a mainconduit leading to a source of fluid under pressure; a plurality of branch conduits connecting said main conduit with said cylinders, the number of said branch conduits being at least twice the number of said rows, each of said rows having a plurality of branch conduits assigned to it and having its cylinders divided into subgroups of at least two cylinders each, the cylinders of each subgroup being juxtaposed more closely than the subgroups of each row, the cylinders of each subgroup being individually connected to respective branch conduits assigned thereto; check-valve means in the fluidsupply path of all the cylinders of a row between the cylin- V ders and said main conduit; and individual shut-oft means for said fluid in each branch conduit between said main conduit and the cylinders connected thereto.

9. A system as defined in claim 8 wherein the cylinders of each subgroup are provided with pistons joined together in a common foot plate bearing upon the pressplaten.

References Cited by the Examiner UNITED STATES PATENTS 715,365 12/02 French 269 X 1,907,083 5/33 Meyercord et al 100-269 X 2,071,999 2/37 Dike 144-281 2,217,652 10/40 Quick 100-269 X 2,363,779 11/44 Duffy et a1 100-269 X WALTER A. SCHEEL, Primary Examiner.

"new 

1. A HYDRAULIC SYSTEM FOR ACTUATING A MOVABLE PRESS PLATEN, COMPRISING A PLURALITY OF PISTON CYLINDERS GROUPED IN SEVERAL ROWS, SAID CYLINDERS BEING PROVIDED WITH PISTON MEANS BEARING UPON SAID PRESS PLATEN; A MAIN CONDUIT LEADING TO A SOURCE OF FLUID UNDER PRESSURE; A PLURALITY OF BRANCH CONDUITS CONNECTING SAID MAIN CONDUIT WITH SAID CYLINDERS, THE NUMBER OF SAID BRANCH CONDUITS BEING AT LEAST TWICE THE NUMBER OF SAID ROWS, EACH OF SAID ROWS HAVING A PLURALITY OF BRANCH CONDUITS ASSIGNED TO IT AND HAVING ITS CYLINDERS OF EACH SUBGROUPS OF AT LEAST TWO CYLINDERS EACH, THE CYLINDERS OF EACH SUBGROUP BEING INDIVIDUALLY CONNECTED TO RESPECTIVE BRANCH CONDUITS ASSIGNED THERETO; CHECK-VALVE MEANS IN THE FLUID-SUPPLY PATH OF ALL THE CYLINDERS OF A ROW BETWEEN THE CYLINDERS AND SAID MAIN CONDUIT; AND INDIVIDUAL SHUT-OFF MEANS FOR SAID FLUID IN EACH BRANCH CONDUIT BETWEEN SAID MAIN CONDUIT AND THE CYLINDERS CONNECTED THERETO. 